X11::Protocol::Ext::DAMAGE(3)
NAME
X11::Protocol::Ext::DAMAGE - drawing notifications
SYNOPSIS
use X11::Protocol;
my $X = X11::Protocol->new;
$X->init_extension('DAMAGE')
or print "DAMAGE extension not available";
my $damage = $X->new_rsrc;
$X->DamageCreate ($damage, $drawable, 'NonEmpty');
sub my_event_handler {
my %h = @_;
if ($h{'name'} eq 'DamageNotify') {
my $drawable = $h{'drawable'};
$X->DamageSubtract ($damage, 'None', $parts_region);
# do something for $parts_region changed in $drawable
}
}
DESCRIPTION
The DAMAGE extension lets a client listen for changes to drawables
(windows, pixmaps, etc) due to drawing operations, including drawing
into sub-windows which appears in the parent.
This can be used for various kinds of efficient copying or replicating
of window contents, such as cloning to another screen, showing a
magnified view, etc. The root window can be monitored to get changes
on the whole screen.
Content changes due to drawing are conceived as "damage". A server-
side damage object accumulates areas as rectangles to make a server-
side "region" per the XFIXES 2.0 extension (see
X11::Protocol::Ext::XFIXES)
A DamageNotify event is sent from a damage object. A reporting level
controls the level of detail, ranging from just one event on becoming
non-empty, up to an event for every drawing operation affecting the
relevant drawable.
Fetching an accumulated damage region (or part of it) is reckoned as a
"repair". It doesn't change any drawables in any way, just fetches the
region from the damage object. This fetch is atomic, so nothing is
lost if the listening client is a bit lagged etc.
See examples/damage-duplicate.pl for one way to use damage to duplicate
a window in real-time.
REQUESTS
The following requests are made available with an "init_extension()",
as per "EXTENSIONS" in X11::Protocol.
my $is_available = $X->init_extension('DAMAGE');
DAMAGE 1.0
"($server_major, $server_minor) = $X->DamageQueryVersion
($client_major, $client_minor)"
Negotiate a protocol version with the server. $client_major and
$client_minor is what the client would like, the returned
$server_major and $server_minor is what the server will do, which
might be less than requested (but not more).
The current code supports up to 1.1. If asking for higher then be
careful that it's upwardly compatible. The module code negotiates
a version in "init_extension()" so explicit "DamageQueryVersion()"
is normally not needed.
"$X->DamageCreate ($damage, $drawable, $level)"
Create a new damage object in $damage (a new XID) which monitors
changes to $drawable. If $drawable is a window then changes to its
subwindows are included too.
# listening to every change on the whole screen
my $damage = $X->new_rsrc;
$X->DamageCreate ($damage, $X->root, 'RawRectangles');
$level is an enum string controlling how often "DamageNotify"
events are emitted (see "EVENTS" below).
RawRectangles every change
DeltaRectangles when damage region expands
BoundingBox when damage bounding box expands
NonEmpty when damage first becomes non-empty
"$X->DamageDestroy ($damage)"
Destroy $damage.
"$X->DamageSubtract ($damage, $repair_region, $parts_region)"
Move the accumulated region in $damage to $parts_region (a region
XID), and clear it from $damage.
If $parts_region is "None" then $damage is cleared and the region
discarded. This can be used if for example the entire $drawable
will be copied or re-examined, so the exact parts are not needed.
$repair_region is what portion of $damage to consider. "None"
means move and clear everything in $damage. Otherwise
$repair_region is a region XID and the portion of the damage region
within $repair_region is moved and cleared. Anything outside is
left in $damage.
If anything is left in $damage then a new "DamageNotify" event is
immediately sent. This can be good for instance if you picked out
a $repair_region corresponding to what you thought was the window
size (perhaps from the "geometry" field of a "DamageNotify" event),
but it has grown in the interim.
Region objects here can be created with the XFIXES 2.0 extension
(see X11::Protocol::Ext::XFIXES). It should be available whenever
DAMAGE is available. If using "None" and "None" to clear and
discard then region objects are not required and there's no need
for an "init_extension('XFIXES')".
DAMAGE 1.1
"$X->DamageAdd ($drawable, $region)"
Report to any interested damage objects that changes have occurred
in $region (a region XID) of $drawable.
This is used by clients which modify a drawable in ways not seen by
the normal protocol drawing operations. For example an MIT-SHM
shared memory pixmap modified by writing to the memory (see
X11::Protocol::Ext::MIT_SHM), or the various "direct rendering" to
graphics hardware or GL etc.
EVENTS
"DamageNotify" events are sent to the client which created the damage
object. These events are always generated, there's nothing to select
or deselect them. The event has the usual fields
name "DamageNotify"
synthetic true if from a SendEvent
code integer opcode
sequence_number integer
and event-specific fields
damage XID, damage object
drawable XID, as from DamageCreate
level enum, as from DamageCreate
more boolean, if more DamageNotify on the way
time integer, server timestamp
area arrayref [$x,$y,$width,$height]
geometry arrayref [$rootx,$rooty,$width,$height]
"drawable" and "level" are as from the "DamageCreate()" which made the
"damage" object.
"more" is true if there's further "DamageNotify" events on the way for
this damage object. This can happen when the "level" means there's a
set of "area" rectangles to report.
"area" is a rectangle within "drawable", as a 4-element arrayref,
[ $x, $y, $width, $height ]
What it covers depends on the reporting level requested,
o "RawRectangles" -- a rectangle around an arc, line, etc, drawing
operation which changed "drawable".
o "DeltaRectangles" -- an additional rectangle extending the damage
region. Only new rectangles are reported, not any of the existing
damage region. Reporting a region addition may require multiple
"DamageNotify" events.
o "BoundingBox" -- a bounding box around the damage region
accumulated, bigger than previously reported.
o "NonEmpty" -- umm, something, maybe the entire drawable.
"geometry" is the current size and position of the drawable as a
4-element arrayref in root window coordinates. For a pixmap $root_x
and $root_y are 0.
[ $root_x, $root_y, $width, $height ]
ENUM TYPES
The reporting level above is type "DamageReportLevel". So for example
(after a successful "$X->init_extension('DAMAGE')"),
$number = $X->num('DamageReportLevel', 'RawRectangles');
$string = $X->interp('DamageReportLevel', 3);
See "SYMBOLIC CONSTANTS" in X11::Protocol.
ERRORS
Error type "Damage" is a bad $damage resource XID in a request.
BUGS
The server extension version number is queried in the
"init_extension()", but not yet made available as such. The version
determines whether "DamageAdd()" ought to work. Currently that request
is always setup, but presumably generates an Opcode error if the server
doesn't have it.
SEE ALSO
X11::Protocol(3), X11::Protocol::Ext::XFIXES(3)
/usr/share/doc/x11proto-damage-dev/damageproto.txt.gz,
<http://cgit.freedesktop.org/xorg/proto/damageproto/tree/damageproto.txt>
HOME PAGE
<http://user42.tuxfamily.org/x11-protocol-other/index.html>
LICENSE
Copyright 2011, 2012, 2013, 2014, 2017 Kevin Ryde
X11-Protocol-Other is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 3, or (at
your option) any later version.
X11-Protocol-Other is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License along
with X11-Protocol-Other. If not, see <http://www.gnu.org/licenses/>.
perl v5.28.2 2017-04-23 X11::Protocol::Ext::DAMAGE(3)
x11-protocol-other 31 - Generated Tue Aug 6 15:25:52 CDT 2019